Data Sheet

ADL8121

THEORY OF OPERATION

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Rev. A | 18 of 22

The ADL8121 is a GaAs, MMIC, pHEMT, low noise wideband am-

plifier. Figure 77 shows the simplified architecture of the ADL8121.

The ADL8121 has single-ended input and output ports with impe-

dances that nominally equal 50 Ω over the 0.025 GHz to 12 GHz

frequency range.

It is critical to supply low inductance ground connections to the

GND pins as well as to the backside exposed pad to ensure stable

operation.

To achieve optimal performance from the ADL8121 and prevent

damage to the device, do not exceed the absolute maximum ratings

(see Table 3).

The RBIAS pin is used to set the IDQ with an external resistor, which

allows single positive supply operation.

Figure 77. Simplified Architecture